The KC-10 did not require modification to carry the SR-71’s special JP-7 fuel, as it had fuel tanks that could be isolated (if desired) and only delivered to the boom. Those tanks could also hold regular JP-8 and feed it to the engines if needed.
Last week, the KC-10 Extender, a superb aerial refuelling aircraft, retired. We spoke to a KC-10 pilot to learn about ‘Big Sexy’.
The best KC-10 was its versatility and the flexibility of its crews. Unlike the KC-135, the KC-10 was ready to refuel probe or drogue receivers without any extra work or attachments needed before launch. With the ability to be refuelled itself, the KC-10 could be launched and flexed to almost any refuelling mission quickly.
The worst thing about the KC-10 was taxiing it around on smaller airfields. The nosewheel sits 20+ feet behind the pilots, so you must be very careful about turning sharp corners or trying 180° turns. In these cases, we’d often have a boom operator open the forward doors, lay on their stomach & hang out of the aircraft; they were on the intercom, relaying the position of the main and nose wheels to the pilots, keeping us from crunching taxi lights or ending up in the grass (which we sometimes did anyway).
Based on overall capacity, the KC-10 was better than the KC-135; it could take off with a much higher fuel load. While it burned more per hour, there was still significantly more fuel available for receivers. The ‘135 also couldn’t do Drogue receivers unless the boom was modified ahead of time (which meant it couldn’t do probe receivers) or if you attached pods to the wings. The KC-10 was ready for either at any time (and we could put our own pods on the wings, if needed).
The empty weight of the KC-10 was about 250,000 lbs. Maximum takeoff weight was 590,000 lbs…so about 340,000 lbs of fuel, if you weren’t carrying cargo. All of it could be offloaded, other than what we needed to save to get ourselves home…and sometimes we pushed that limit! In one case, I pushed a little too far – we got back to our deployed base, and it was fogged in. We couldn’t even attempt an approach.
We were getting close to diverting, which would have been painful, but another KC-10 arrived. They took up a holding pattern over the base, a couple thousand feet above us. We started coordinating between ourselves to balance fuel out so nobody had to divert, then just did it. At one point, there were four of us in the pattern, talking to each other, and passing fuel so that everyone got to sleep in their own bunks. The fog eventually lifted, and we all made it in.
The KC-10 was actually pretty easy to take off and land. It was very stable and large, and bumps that would affect smaller jets didn’t have much impact on us. The controls were pretty straightforward. On landing, you’d start the process of “flaring†just after the 50’ radar altimeter callout.
You rarely landed smoothly, though, as the centre gear touched down first on crowned runways. It shook & rattled, so there was always some of that, except in the rare instance you’d land with the centre gear retracted.
There weren’t many foibles to the jet; it handled well. It was just very large. When refuelling with KC-135s years ago, the bow wave of a heavy KC-10 could hit a sensor in the 135’s tail, disconnecting their autopilot. If they weren’t watching it, you’d suddenly end up with a face-full of KC-135 as their autopilot kicked off and the nose dropped. They eventually fixed that problem, if I recall.
One peculiar aspect was that the number 2 engine in the tail was angled down at about 2.5°. We tried not to use it for taxiing, as we were already worried about blowing things over…some would limit how much they used it when air refuelling, too, as a big input could push the nose down.
Something you may not know about the KC-10: well, it had a large space under the cargo floor that was just empty. I think it was the galley on the DC-10, but the Air Force had no need. We called it “The Pool Roomâ€; I was told it was because you could put a pool table in there, and have room to play. Getting into it was a hassle.
You could access the KC-10 through the nose gear. We occasionally had to do that; you’d climb up & shimmy through the avionics compartment, eventually ending up in the cockpit. It was a tight fit!
The newer KC-46 is a decent aircraft. It’s had teething issues, but they will eventually sort it out. The problem is that losing the KC-10 still represents a major loss of overall capacity, as there will be less fuel in the air at any given time. The Air Force already can’t meet all its demand for Air Refueling, and I’m afraid that is much worse today.
My favourite aircraft to refuel was the B-1; it wasn’t particularly cool or anything, but when it showed up on your schedule in Afghanistan, they were going to take about 100k lbs of fuel…and your day just got a lot shorter!
My least favourite aircraft to refuel was the A-10. It doesn’t have the power of other jets and flies pretty slowly; we had to use slats and sometimes flaps to get slow enough. Above certain weights, it was just not possible.
The deck angle when refuelling A-10s could be in excess of 5° nose up…almost feels like you are setting up for a power-on stall. We had a procedure to help called a “Tobogganâ€â€¦we’d enter a slight descent at around 300 feet per minute. That gave the A-10 the help it needed to get on the boom, but you only had 1,000’ below you before you’d be outside of your protected airspace, so you’d only get 3 minutes or so. Then you’d have to climb up & do it again.
Nobody was necessarily bad at meeting the tanker, and we went out of our way to come to them. It didn’t always work, but we usually managed to end up 1-3 miles in front of them. Many fighter types referred to the KC-10 as the “mothership†because it was so large and was just there, in front of you.
Occasionally, the AWACs would control our rejoins. They didn’t seem to have much practice doing so; I can recall them vectoring us to our bomber, and vectoring the bomber to us…AWACs handed us off nose to nose at around 3 miles, closing at probably 600-700 knots. We were separated by 1,000’, so it wasn’t unsafe, but AWACs kind of said, “There you go,†and we immediately shot past each other in opposite directions. It was funny…we took over & directed a mutual turn on the same magnetic heading, which at least put us abeam each other & fixed it from there.
The KC-10 set the bar for tanker ops, hands down. As we discussed, the flexibility to do any Air Refueling mission at any time was key, and our ability to be refuelled meant we could be doing it for long hours.
We also had a significant cargo capacity. You could load up support troops and their equipment, then drag multiple fighters across an ocean. When you landed, you were almost your own little Air Force and could start operations quickly.
1A good tanker crew got to be a mini family. We didn’t use ranks in the KC-10 while flying, but rather, first names. We wanted every member of the crew to feel like they could speak up if they saw something wrong; everyone knew who the Aircraft Commander was, but that wasn’t something you wanted to flex on your crew – doing so may mean you win the battle, but you’re losing the war.
A good crew got to the point where they knew what everyone else needed, and they were ready before anyone asked. They understood the bigger picture, and took care of each other; you could complain, but my only rule was that the complaints better be funny because there wasn’t a lot we could do about most of it…it was better to laugh about it than to make each other miserable.
Big Sexy was the most common name, yes. Sometimes referred to as Gucci, but the official name was the Extender.
Three engines weren’t particularly unusual, no. The tail engine was exactly like the other two, but with a longer cowling. It was angled down slightly, though, as I mentioned.
If you had an engine failure (like we did in the simulator every quarter), you hoped it would be the tail engine. There was no asymmetrical thrust; the loss of one of the wing engines caused a lot of asymmetrical thrust, which required a lot of rudder to counteract.
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Living under the flightpath to RAF Mildenhall, I used to see a lot of KC-135s, Starlifters and even E-3s coming and going. C-5s and the spookies – SR-71s, RC-135s and TR-1s – were obviously rarer and a bit special. For some reason, though, I was always particularly fond of the KC-10. They only showed up occasionally (unlike the rest I don’t think they were based there, only visitors) but they were big and unusual and distinctive and I knew if they were there, they’d come a long way from somewhere else. Safe travels, Big Sexy. o7